Spatial proteomics and cell-cell crosstalk analysis reveal PD-L1 and IL-6 interaction in human primary sclerosing cholangitis

BACKGROUND & AIMS: Primary sclerosing cholangitis (PSC) is a chronic, immune-mediated cholangiopathy characterized by persistent inflammation and fibrotic remodelling of the biliary tree. We combined spatial proteomics of PSC-affected large bile ducts with a co-culture system of biliary epithelial cells (BECs) and activated peripheral blood mononuclear cells (aPBMCs) to dissect the molecular crosstalk at the epithelial-immune interface. METHODS: Spatial proteomic analysis was performed on six PSC-affected bile ducts and five healthy controls by GeoMx® DSP. Single-cell RNA-sequencing analysis from publicly available datasets of human control (n = 22) and PSC-affected (n = 8) livers was performed. We developed an in vitro inflammatory model of PSC by transwell co-culture of BECs (i.e. H69 and primary human biliary tree stem cells) and primary human PBMCs (n = 6). Co-cultures were analysed by transcriptomics on nCounter®, by immunoassays and by culture with/without blocking agents. RESULTS: ) and NK cells. In co-culture, the exposure of BECs to the IL-6/sIL-6R complex induced significant PD-L1 upregulation (12.7 ± 1.3; p